The demand for poultry, and especially chicken feet (sometimes called paws) as a specialty food item, particularly in Asia, is relatively great. After paws are removed from chickens during processing, the paws are graded according to various quality factors. The value of a paw varies greatly depending on the grade.
There are three principal grades: condemned grade, sub-grade, and A-grade. Condemned grade paws are used primarily as a component in animal feeds. Sub-grade and A-grade paws are used principally for human consumption. An A-grade paw may be worth in the range of ten times that of a condemned paw, and several times a sub-grade paw. Therefore, it would be commercially advantageous to minimize the number of paws that are classed as condemned grade and to maximize the number of paws that are classed as A-grade.
Typically, sorting of paws by grade is done by hand upon visual inspection, separating paws from one stream into three. This can be a time consuming exercise, and often results in many paws being graded condemned or sub-grade.
One of the principal factors causing a paw to be graded below A-grade is the presence and size of dark sores or lesions on the paw, for example on the metatarsal pad. These sores (also sometimes called blisters) often are urea/ammonia burns that arise from contact between the chicken and chicken feces present on the floor where the chicken is kept. FIG. 1 shows a paw 20 with a large lesion 22 on a bottom surface that would mandate a reduced grade for the paw.
Certain methods have been used to prevent the burns from occurring, including treating the chicken houses with ammonium bisulfate or dilute phosphoric acid in order to reduce the corrosive nature of the ammonia present. Bacterial treatment of the ammonia has also been used. These methods are all preventative in nature and are only partially effective in preventing lesion formation. There are also cost chemical safety issues with such treatments.
It has also been proposed to remove lesions from the paws in an attempt to improve grading. This removal can be done manually. However, there are drawbacks to manual removal. First, manual removal is labor intensive and time consuming, therefore expensive. Also, it is difficult to fully remove a lesion by hand with a sharp object without otherwise damaging the paw, leading to grade below A-grade.
Removal has also been proposed via mechanically driven brush-type or rubber finger contact based systems, which essentially scrape the paw surfaces in an attempt to remove the lesions. However, these systems are also destructive to the paws, again often leading to a grade below A-grade.
Accordingly, a device, system and method that can remove lesions from chicken paws while addressing one or more drawbacks of discussed above or others would be welcome.